#include <stdio.h>

struct ListNode {
	int val;
	struct ListNode *next;
	ListNode(int x) :
			val(x), next(NULL) {
	}
};

class Solution {
public:
    ListNode* ReverseList(ListNode* pHead) {
        if (pHead==nullptr)
            return nullptr;
        
        ListNode* preNode=nullptr;
        ListNode* nextNode=nullptr;
        ListNode* curNode=pHead;
        
        while(curNode!=nullptr){
            nextNode = curNode->next;
            curNode->next=preNode;
            preNode=curNode;
            curNode=nextNode;
        }
        return preNode;
    }
};
